In 2013, the Institute of Medicine, (now the Health and Medicine Division) and the National Research Council of the National Academies of Sciences, Engineering, and Medicine (the National Academies) convened a planning committee to plan and conduct a two-day public workshop that reviewed updates to the 1982 Institute of Medicine (IOM)-National Research Council (NRC) report, Research Issues in the Assessment of Birth Settings. The 8-person committee was chaired by Maxine Hayes, M.D., M.P.H., State Health Officer for the State of Washington. The workshop discussion spanned a broad range of issues related to the effects of maternal care services in different birth settings on labor, clinical and other birth procedures, and birth outcomes, including historic and recent trends in childbirth and birth settings, assessment of risk in pregnancy, health outcomes associated with birth setting, workforce issues related to birth setting, data systems and measurement, and cost and reimbursement issues. The major themes that were raised by the participants during the workshop are as follows: ? While much of the workshop discussion revolved around general differences between hospital, birthing center, and home birth settings, several workshop participants elaborated on the variability within each setting with respect to physical environment, care, and patient experience. ? Since 1982, researchers have gathered a great deal of data and information about birth setting trends, outcomes, and related issues. However, several participants opined that, while the lists of what has been learned are long, the list of what still needs to be learned is longer. ? Many participants elaborated on the importance of vital statistic data (e.g., U.S. birth certificate data) and the need to improve the quality of such data. While the gathering of information has improved since 1982, for example, with the distinction between home and birthing center births added to the U.S. birth certificate in 1989, the importance of accurate reporting is underappreciated. ? There was a great deal of discussion about the risks and safety of birth, with topics ranging from varying definitions of ?low risk? to varying perceptions of risks and safety (i.e., different women have different perceptions of what is safe). In addition, there were discussions about the need for greater public and provider understanding of risk, including differences between absolute and relative risk. ? There were several calls for more randomized controlled trials of health outcomes among different types of birth settings; at the same time, the difficulty of conducting such studies (i.e., the difficulty of randomizing participants among birth settings) was recognized. ? There was much discussion about birth outcomes as related to the birth setting, with several presenters observing that the birth center and home birth settings have been associated with fewer interventions, fewer complications, high transfer rates, and an increased risk for neonatal mortality with home births. The latter finding was deemed controversial. ? While one of the purposes of birth setting research is to inform policy and practice, workshop participants considered how developing and implementing national standards will be difficult due to state-level variation in birth and birth setting trends, provider regulation and liability, and Medicaid coverage for maternal and neonatal care. ? Several workshop participants expressed concern about choice of birth setting and the need to better inform women about available options, and disparity in access to various birth settings and specific services. They suggested there is a need to increase access to a wider range of settings, services, and care providers and to opportunities for transfer from out-of-hospital settings to a hospital if the need should arrive. ? The lack of trust among different types of care providers was a prevailing theme, with many participants calling for the need to improve interprofessional education, communication, and interaction. Although epidemiologic data are limited in the United States, according to the Centers for Disease Control and Prevention an estimated 700 women die each year from conditions related to pregnancy or childbirth, one of the higher maternal mortality rates in the developed world. There is also a high incidence of maternal morbidity. Further study into the birth settings chosen by sub-populations of women in the United States and the factors that go into those decisions is thus warranted. In particular, reviewing the current state of science to determine what birth/health outcomes experienced by sub-groups of women who give birth in different types of settings is a priority.